POSIDONIUS pŏs’ ĭ dō’ nĭ əs (Ποσιδώνιος, Posidon, i.e. a man dedicated to the god of the sea, Posidon [or Neptune]). Mentioned in 2 Maccabees 14:19 as one of three envoys sent by the Syrian general Nicanor to Judas the Maccabee with authority to propose and accept a truce.